G4S security guards have violently removed more than a dozen protesting shareholders from the company's annual meeting .

Protesters, who bought shares in the firm in order to attend the meeting, were dragged out of the conference room in the Excel Centre, London, on Thursday after speaking out about its role supplying Israeli prisons and the death of an Angolan man while he was being deported by G4S guards.

One protester who had attached herself to a chair was manhandled by four security guards. "You are hurting me, you are hurting me," she said as she was dragged from the meeting.

A leaflet she left behind said: "We are here because G4S helps governments across the world to violate basic human rights.

"We want to remind you that the huge salaries your board earns and the dividends that your shareholders pocket are only possible because of the extreme human suffering that G4S inflicts."

Another protester was violently evicted by two guards after he spoke out about the death of Angolan national Jimmy Mubenga.

"Shame on G4S from making illegal deportations. Who killed Jimmy Mubenga?"

John Connolly, the firm's chairman, banned the Guardian from tweeting or live reporting from the meeting. G4S security guards prevented shareholders from taking photographs or videos of the violent removal of protesters.

A shareholder interrupted proceedings to question the board about the violent removal of protesters. He said: "This cannot be acceptable. You can not have people being dragged out."

Another shareholder said: "We feel very uncomfortable about our company doing this."

A total of 29 security guards and other personnel were positioned around the room.

G4S investor Shamiul Joarder said the violent behaviour of guards evicting protesting shareholders was shocking. "I'm really taken aback and a little shook up and a little bit scared," he said. "What really worries me is this is the AGM this is the creme de la creme. It doesn't bode well for how G4S deals with people on the ground if the board allows this behaviour."

Chris Rose, a proxy shareholder and vicar of St Clement East Cheapside, said the behaviour of guards was ridiculous. "I haven't been eyeballed this much since Chelsea [football matches] in the 1980s.

"This is the leading company in an area that needs an ethical approach."

Will McMahan, another shareholder, said: "I found the way people sitting next to me were dragged out was profoundly shocking, and it will stay with me for a long time."

Peter Ridsdalesmith, 68, a private shareholder said he had suffered "nothing but blessed disaster" since buying shares in the company two years ago.

"The Olympics, Israel, it's been nothing but lashups. This hasn't been a friendly meeting, I wanted to go home reassured."

Connolly said: "None of us enjoy being in a meeting like this. Hopefully, step-by-step, we are changing the company."

Speaking to the Guardian after the meeting, he denied that protesting shareholders were treated violently by the company's guards. He said protesters were warned at the start of the meeting that if they caused a disruption they would be asked to leave the meeting.

"If someone refuses to leave and lies down on the floor they will be assisted to leave," he said. "I saw one person carried out, how else do you get someone to leave if they continue [to protest] without helping them out? I do not expect any complaints on how people were taken out."

Ashley Almanza, G4S chief executive, said he thought his guards "showed due care and attention" and "I do not believe it was violent" behaviour.

G4S has denied any involvement in torture or human rights abuses. Connolly said the company had already decided not to renew its contracts to maintain prisons in Israel and the West Bank.

Almanza said: "We do not operate prisons, we supply prisons with security equipment."

He added that the equipment made the Israeli prisons safer and did not increase the risk of human rights abuses.

An independent human rights report commissioned by G4S following similar protests at last year's AGM found the company "had no causal or contributory role in human rights violations".

"There are clearly human rights failings in some parts of Israel's security system, but G4S's role is far removed from their immediate causes and impact," the report by Hugo Slim, a research fellow at the Institute of Ethics, Law and Armed Conflict at the University of Oxford, said.